On June 26, an Asplundh Tree Company truck maneuvered past the Glen Canyon Park Recreation Center, pulled adjacent to a eucalyptus tree that hosts owls each winter and stopped before a young woman taking notes.

A mother, escorting her daughter to Silver Tree summer camp, gestured toward the familiar tree. She pointed skyward, directing her little girl to a quilt of leaf-cushioned branches where, until recently, a mother Great Horned Owl had served her nestlings daily meals of mice, squirrels and sparrows.

Jessica Peak, biologist from Transcon Environmental, retained by PG&E to ensure that there remain no nesting owls in eucalyptus tree before pruning branches that overhang electric wires.

The Silver Tree mother and the young woman chatted for a while. Jessica Peak, a biologist from Transcon Environmental, laid down her notebook and walked toward a Spanish-speaking tree trimmer, who’d strategically placed orange warning cones along Alms Road. Peak directed him to a leafy V in the gum tree canopy, which until April had served as bedding for a brood of baby owls. The nest, embroidered with a coverlet of nut-tanned leaves, spongy and soft, had earlier dropped a deciduous blanket of brittle leaf litter to the ground.

Peak stepped on the leaves, some snapping like splintery crackers. “We’re here to ensure there isn’t an active nest,” said Peak, who holds a degree in conservation biology from San Francisco State University.

Other parents, accompanying their children to Silver Tree Camp, crooked their arms, straining to get a look. “Is the owl still there?” one asked. Great Horned Owls are known to usurp bird nests, even those of Red-tailed Hawks, making their homes in tree cavities, even large gaps, using feathers and leaves as cushions. Now, evidence of an owl recently domiciled in the towering eucalyptus, so much a part of Glen Park familial lore, was absent.

The Great Horned Owls are fiercely protective of their young. The female can produce up to five eggs a year, but on average two. While the mother owl, who is actually larger than the male, roosts with her young, the father hunts, bringing back nocturnal repast for his incubating offspring. One of our most efficient coastal predators, the Great Horned Owl has a singular digestive system, even capable of consuming its prey whole.

PG&E subcontracts with Asplundh to remove dangling branches that threaten its electrical lines. But the utility company also wishes to ensure that its routine pruning doesn’t endanger natural wildlife, particularly in an urban oasis such as Glen Canyon, which the Recreation and Parks Natural Areas Program manages. “We do tree maintenance work,” said Jon Campo, a NAP steward, “after the nesting season.”

Peak had only recently returned from the Central Coast. “I just checked out a hot nest in Watsonville,” she said. “I make sure that any pruning doesn’t harm habitat.”

A Great Horned Owl can grow from 17 to 27 inches with a wingspan of 39-60 inches and weigh up to six pounds. Its talons are lethal, capable of dismembering unsuspecting feral cats, even eviscerating raccoons and skunks. Easily recognizable by their cat-like ears that resemble horns, Great Horned Owls are monogamous, adaptable enough to live in disparate places such as the Arctic and South America, their photogenic tufts of ear feathers peaking to regal crowns.

Randy Zebell, a NAP cohort of Campo, chimed in: “Owls nest between December and April,” he said, “and hatching occurs from January to February.”

The eucalyptus tree, anchored to the canyon’s floor, has been rooted in Californians’ arboreal DNA since the Gold Rush, and is recognized as an integral part of Glen Canyon’s diverse habitat.

Peak and Rachel Kessel, another NAP steward, women watched a worker high above the truck bed, ensconced safely in a waist-high basket. He cut a limb brushing against an overhanging wire, far away from the owl’s vacated perch. His ground level cohorts collected the fallen limbs and removed them to the edge of the path, away from several dog walkers.

Incubation, which normally takes 33 days on the average, has been finished for several months now. Owl brooding is almost continuous until the juveniles are about two weeks old and by six weeks the fledglings move to nearby branches. By 10 to 12 weeks they are competent flyers.

The Great Horned Owl is widely distributed through North America, its hunting prowess secured by its specialized hearing and human-sized eyes. Suited for secrecy and stealth, camouflaged by its cloak of brownish down, it gives itself away, though, by its distinctive vocalizing.

Glen Canyon birders who walk along Alms Road in the early morning or evening can elevate their eyes during the correct season of the year and glimpse this statuesque raptor, maybe even watch a mama feeding it youngsters. The “Hoo Hoo’s” exchanged among avian and human is the final word on this long-standing neighborhood tradition.